Lecture 6 Thrombosis, embolism and shock Flashcards
Define thrombosis?
Formation of a solid or semi-solid mass from blood constituents which moves within vascular system.
Where may thrombi form?
1) lumen of heart 2) arteries 3) veins 4) capillaries.
What may aortic thrombus cause?
Ischaemia and emolism to the leg
What may vein thrombus cause?
Oedematous right leg. Deep vein thrombosis. ?after abdo surgery.
What do capillary thrombi cause?
(involves both thrombus formation and haemorrhage). Minute thrombi may cause scattered ischaemic lesions.
Factors that promote thrombosis
Virchow’s triad. Abnormalities of 1) vessel wall 2) Blood flow 3) blood constituents
Factors affecting vessel wall in arteries?
Atheroma, inflammation
Factors affecting vessel wall in heart?
Myocardial infarction, rheumatic endocarditis.
Factors affecting vessel wall in veins?
1) Trauma, inflammation. 2) Chemicals (sclerosants - irritant substances injected to remove varicose veins). 3) Glucose (atheroma in diabetes)
Factors affecting vessel wall in capillaries?
Inflammation
General factors affecting blood flow?
Heart failure or circulatory shock.
Factors affecting blood constituents?
Polycythaemia, hyperproteinaemia, abnormalities of clotting
What is polycythaemia
abnormally ^ haemoglobin
What can make someone have polycythaemia?
Dehydration, polycythaemia rubra vera or chronic hypoxia.
What can lead to hyperptoteinaemia?
Multiple myeloma (tumour of plasma cells in bone marrow with accumulation of immunoglobins in plasma)
What can cause abnormalities of clotting?
Pregnancy (Xbleeding when placenta detaches). Older contraceptive pills, following trauma (liver produces more clotting factors). Thrombocythaemia.
Define thrombocythaemia
High platelet count in blood
What are the three thrombi fates?
Resolution (fibrinolysis), Organisation (incorporated into scar by macrophages/fibroblasts), Detachment (thromboembolism)
Define embolism
The transport of abnormal material (solid,liquid or gas) by the blood stream and its impacting in a blood vessel.
Types of emboli
Thrombi, fat (from multiple bone #), gas (infusion/vascular surgery).
What is caisson disease?
When ascending from the depths too rapidly, bubbles of N2 form in blood -> enters bones and joints -> pain known as bends.
How can an air embolus from IV therapy be found?
filled pericardium with water, cut into ventricular cavity, can see bubbles.
Types of emboli? (5)
Tumour material, infective agents, aheroma, amnootic fluid, foreign bodies.
Define shock
A physiological state. Systemic ↓ in tissue perfusion, ↓ oxygen delivery and insufficient removal of metabolic waste -> tissue injury
What causes hypovolaemic shock
Haemorrhage - internal or external. Severe burns.
What causes cardiogenic shock
Large acute myocardial infarction, other acute cardiac disease.
What causes neurogenic shock
Spinal cord trauma, regional anaesthesia.
What causes obstructive shock
Cardiac tamponade, tension pneumothorax, massive pulmonary embolism
Define cardiac tamponade
Define tension pneumothorax
build-up of air in pleural space. Due to lung laceration -> allows air into the pleural space.
What causes septic shock
Endotoxins (gram negative), exotoxins (gram positive). Both -> blood vessels dilating
What causes anaphylactic shock?
Severe form of allergic reaction
Clinical features of shock: BP?
↓BP
Clinical features of shock: HR?
Tachy >90bpm
Clinical features of shock: RR?
29 breaths per minute
Clinical features of shock: Urine output?
Low
Clinical features of shock: blood vessels?
Cutaneous vasoconstriction/vasodilation
Clinical features of shock: feelings?
anxiety, agitation OR indifference, lethargy, obtunded.
Clinical features of shock: Additional?
Hypoxia, metabolic acidosis.
